Makroalgen

Makroalgen, or macroalgae, are large, photosynthetic, multicellular algae that inhabit marine and brackish environments. They are not true plants and lack lignified tissues. Macroalgae are traditionally grouped into brown algae (Phaeophyceae), red algae (Rhodophyta), and green algae (Chlorophyta). They occur from the intertidal zone to open coasts, and some species inhabit freshwater.

These groups differ in pigments: brown algae with fucoxanthin, red algae with phycoerythrin, green algae with chlorophylls a and b. They store energy as laminarin or mannitol (brown), floridean starch (red), or starch (green).

Macroalgae are important primary producers and form coastal habitats such as kelp forests, providing food and shelter for diverse fauna and contributing to nutrient cycling and carbon sequestration.

As food, they are consumed in many cuisines. Examples include nori (Porphyra/Pyropia), kombu (Laminaria), wakame (Undaria pinnatifida), and sea lettuce (Ulva). They also yield phycocolloids—alginate from brown algae; agar and carrageenan from red algae—used as thickeners and gelling agents in food, cosmetics, and industry.

Cultivation of macroalgae—seaweed farming—is widespread and growing in China, Indonesia, Japan, Korea, and parts of Europe. It can provide sustainable biomass and help mitigate nutrient pollution, but faces challenges such as disease, warming waters, invasive species, and regulatory issues.

Reproduction varies by species and often involves alternating generations with haploid and diploid stages.